The mean 13C labeling of the TCA cycle intermediates (glutamate, citrate, fumarate, malate, and aspartate) derived from [13C5]-glutamine anaplerosis into the first turn of the TCA cycle were higher in CD138+ malignant plasma cells from MM patients compared to the remainder of their paired CD138- mononuclear cells. The gene discussed is SDC1; the disease is Miyoshi myopathy.